Confronted with a trend of increasingly severe hazy weather, the government has accelerated the pace of quality upgrading of gasoline and diesel, and state IV emission standard for oil products was nationally implemented in 2014, which requires the sulfur content of gasoline to be decreased to less than 50 ppm; meanwhile state V quality standard was put forward, which requires the sulfur content of gasoline below 10 ppm, and was implemented in Beijing, Shanghai and Guangzhou in 2013 firstly. The catalytic cracking gasoline accounts for a share of about 70˜80% of domestic gasoline product components, and thus as a matter of fact, gasoline desulfurization mainly refers to catalytic cracking gasoline desulfurization.
Existing representative technology for desulfurizing catalytic cracking gasoline includes Chinese Sinopec's S-zorb and Research Institute of Petroleum Processing's RSDS and French Prime-G+. The S-zorb is initially developed by U.S. Conocophillips company, and is bought out and improved by China Sinopec Corporation. The S-zorb is used for desulfurizing full-range catalytic gasoline, and after desulfurizing, sulfur content may be controlled below 10 ppm and octane number loss of the full-range gasoline is 1.0˜2.0 units. The RSDS is developed by Research Institute of Petroleum Processing, this technology separates the catalytic gasoline into light and heavy fractions firstly, wherein the light fractions are sweetened by extraction, and the heavy fractions are subjected to selective hydrodesulfurization; when a product having sulfur content of less than 10 ppm is produced by this technology, the yield of light fractions is about 20%, a majority thereof needs to be hydrogenated, and the octane number loss of the full-range gasoline is between 3.0˜40. The Prime-G+ is developed by French Axens company, it uses a process flow of full-range prehydrogenation, light and heavy gasoline separation, and heavy fraction selective hydrodesulfurization, and is characterized in that: during the full-range prehydrogenation, light sulfide is reacted with dialkene to form a sulfide with a high boiling point, wherein the olefin is not being saturated, and then light and heavy gasoline fractions are separated into a light fraction having a sulfur content of less than 10 ppm and a sulfur-rich heavy fraction, with the heavy fraction subjected to hydrodesulfurization; as in the RSDS, although a part of sulfur-poor light components may not be subjected to a hydrogenation treatment, since the yield of the light components with sulfur content of less than 10 ppm is very low, a majority thereof needs the hydrogenation treatment, resulting in that the octane number loss of the full-range gasoline also is between 3.0˜4.0.
In summary, there are many problems, such as a large proportion of hydrogenation treatment in the whole process and high octane number loss, in these existing technologies for reducing sulfur content of catalytic cracking gasoline, when they are used for deep desulfurization of gasoline. There is a pressing need in the market to develop a non-hydrodesulfurization technology with low octane number loss.